Understanding the charge/discharge mechanism of batteries plays an important role in the development of high-performance systems,but extremely complicated reactions are involved.Because these complex phenomena are als...Understanding the charge/discharge mechanism of batteries plays an important role in the development of high-performance systems,but extremely complicated reactions are involved.Because these complex phenomena are also bottlenecks for the establishment of all-sol id-state batteries(ASSB),we conducted multi-scale analysis using combined multi-measurement techniques,to directly observe charge/discharge reactions at hierarchical scales for the oxide-type ASSB using Na as the carrier cation.In particular,all of measurement techniques are applied to cross-section ASSB in the same cell,to complementarily evaluate the elemental distributions and structural changes.From Operando scanning electron microscopy-energy-dispersive X-ray spectroscopy,the Na concentration in the electrode layers changes on the micrometer scale under charge/discharge reactions in the first cycle.Furthermore,Operando Raman spectroscopy reveal changes in the bonding states at the atomic scale in the active material,including changes in reversible structural changes.After cycling the ASSB,the elemental distributions are clearly observed along with the particle shapes and can reveal the Na migration mechanism at the nanometer scale,by time-of-flight secondary ion mass spectrometry.Therefore,this study can provide a fundamental and comprehensive understanding of the charge/discharge mechanism by observing reaction processes at multiple scales.展开更多
In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were charac...In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were characterized by SEM,NH3-TPD and N2adsorption-desorption isotherms to indicate their intrinsic characteristics.Furthermore,in order to understand the mechanism of deactivation,the resulted green oil was characterized using FTIR and SIM DIS.FTIR results confirmed the presence of more unsaturated constituents and then,more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO,which in turn,could block the pores mouths.Besides the limited hydrogen transfer,N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation,compared with the other catalysts,especially at higher temperatures.展开更多
The effects of manganese oxide or ceria promoters on the performance of Na2WO4/SiO2 catalysts for oxidative coupling of methane （OCM） are reported. The OCM reaction was performed in a continuous-flow microreactor at...The effects of manganese oxide or ceria promoters on the performance of Na2WO4/SiO2 catalysts for oxidative coupling of methane （OCM） are reported. The OCM reaction was performed in a continuous-flow microreactor at 800℃, atmospheric pressure and under GHSV = 13200 ml·gCat^-1·h^-1.Catalysts were characterized by in situ conductivity measurement, FT-IR spectroscopy, XRD, SEM and temperature programmed reduction analysis. Manganese oxide promoted Na2WO4/SiO2 is considered as one of the active and selective catalysts for OCM reaction. Ceria with high oxygen storage capacity is selected as a proper oxygen activator, providing a higher concentration of the oxy-anion species which is suitable for OCM reaction and compared with manganese oxide. Electrical conductivity of the catalysts was measured in OCM reaction under oxidizing atmosphere, i.e. in the absence of methane. It was found that the trimetallic catalysts, i.e. the catalysts having sodium, tungsten and Mn or Ce species, exhibited similar crystalline structures and morphologies, which lead to suitable bulk properties for the formation of an active and selective catalyst. However, tungsten had significant effect on the texture and redox properties of the catalysts. It was also shown that the crystalline structure of the bimetallic （Na＋Mn or Ce）/SiO2 samples was quite different. This reveals that the metal oxides have significant effect on the extent of crystallization, taking place in the course of interaction of sodium with silica support. Similar conductivities and catalytic performances of （Na2WO4＋Mn or Ce）/SiO2 catalysts propose that the ability of Na2WO4/SiO2 for utilizing oxy-anions formed in presence of different metal oxides is limited.展开更多
A series of organic compounds were successfully immobilized on an N-doped graphene quantum dot (N-GQD) to prepare a multifunctional organocatalyst for coupling reaction between CO_(2)and propylene oxide (PO).The simul...A series of organic compounds were successfully immobilized on an N-doped graphene quantum dot (N-GQD) to prepare a multifunctional organocatalyst for coupling reaction between CO_(2)and propylene oxide (PO).The simultaneous presence of halide ions in conjunction with acidic-and basic-functional groups on the surface of the nanoparticles makes them highly active for the production of propylene carbonate (PC).The effects of variables such as catalyst loading,reaction temperature,and structure of substituents are discussed.The proposed catalysts were characterized by different techniques,including Fourier transform infrared spectroscopy (FTIR),field emission scanning electron microscopy/energy dispersive X-ray microanalysis (FESEM/EDX),thermogravimetric analysis (TGA),elemental analysis,atomic force microscopy (AFM),and ultraviolet–visible (UV-Vis) spectroscopy.Under optimal reaction conditions,3-bromopropionic acid (BPA) immobilized on N-GQD showed a remarkable activity,affording the highest yield of 98%at 140℃ and 106Pa without any co-catalyst or solvent.These new metal-free catalysts have the advantage of easy separation and reuse several times.Based on the experimental data,a plausible reaction mechanism is suggested,where the hydrogen bonding donors and halogen ion can activate the epoxide,and amine functional groups play a vital role in CO_(2)adsorption.展开更多
1.Introduction Grain boundaries(GBs)in polycrystalline materials exhibit unique atomic structures due to the lattice disorder,resulting in properties that are distinct from the bulk[1-5].Doping foreign atoms in the GB...1.Introduction Grain boundaries(GBs)in polycrystalline materials exhibit unique atomic structures due to the lattice disorder,resulting in properties that are distinct from the bulk[1-5].Doping foreign atoms in the GBs has become one of the most popular strategies for modifying material properties,such as grain growth behaviors,microstructures,and mechanical properties in polycrystals[6-12].These dopants typically diffuse along the GBs at elevated temper-atures and ultimately segregate to preferred GB atomic sites to modify the structures of the GBs[13-15].Consequently,GB seg-regation of dopants has gained significant interests,and a funda-mental understanding of the origin of GB segregation phenomena is crucial for the rational design of materials with unprecedented properties.展开更多
A first-principles-based computational tool for simulating phonons of magnetic random solid solutions including thermal magnetic fluctuations is developed.The method takes fluctuations of force constants due to magnet...A first-principles-based computational tool for simulating phonons of magnetic random solid solutions including thermal magnetic fluctuations is developed.The method takes fluctuations of force constants due to magnetic excitations as well as due to chemical disorder into account.The developed approach correctly predicts the experimentally observed unusual phonon hardening of a transverse acoustic mode in Fe–Pd an Fe–Pt Invar alloys with increasing temperature.This peculiar behavior,which cannot be explained within a conventional harmonic picture,turns out to be a consequence of thermal magnetic fluctuations.The proposed methodology can be straightforwardly applied to a wide range of materials to reveal new insights into physical behaviors and to design materials through computation,which were not accessible so far.展开更多
Concentrations of intrinsic and extrinsic point defects in crystalline materials with a bandgap are typically calculated in a constant-μapproach from defect formation energies based on density functional theory.In th...Concentrations of intrinsic and extrinsic point defects in crystalline materials with a bandgap are typically calculated in a constant-μapproach from defect formation energies based on density functional theory.In this work,calculations of thermal and charge equilibria among point defects are extended to a constant-N approach.The two approaches for point-defect equilibria are comparatively demonstrated in the application to Mg_(2)Si doped with Li,Na,and Ag,which is a lightweight and environmentally friendly thermoelectric candidate material.Our results reveal the systematic behavior of defect and carrier concentrations.The dopant atoms form interstitial defects at similar concentrations to substitutional defects at the Mg sites,resulting in significantly reduced free-carrier concentrations compared to the expected values.The developed procedures could be utilized to find an optimal avenue for achieving higher carrier concentrations,e.g.,with regard to annealing temperature and the concentration of dopant atoms,in various semiconductors and insulators.展开更多
Martensitic transformation with good structural compatibility between parent and martensitic phases are required for shape memory alloys(SMAs)in terms of functional stability.In this study,first-principles-based mater...Martensitic transformation with good structural compatibility between parent and martensitic phases are required for shape memory alloys(SMAs)in terms of functional stability.In this study,first-principles-based materials screening is systematically performed to investigate the intermetallic compounds with the martensitic phases by focusing on energetic and dynamical stabilities as well as structural compatibility with the parent phase.The B2,D0_(3),and L2_(1) crystal structures are considered as the parent phases,and the 2H and 6M structures are considered as the martensitic phases.In total,3384 binary and 3243 ternary alloys with stoichiometric composition ratios are investigated.It is found that 187 alloys survive after the screening.Some of the surviving alloys are constituted by the chemical elements already widely used in SMAs,but other various metallic elements are also found in the surviving alloys.The energetic stability of the surviving alloys is further analyzed by comparison with the data in Materials Project Database(MPD)to examine the alloys whose martensitic structures may cause further phase separation or transition to the other structures.展开更多
基金This article is based on results obtained from a project,Grant JPNP14004,commissioned by the New Energy and Industrial Technology Development Organization(NEDO)。
文摘Understanding the charge/discharge mechanism of batteries plays an important role in the development of high-performance systems,but extremely complicated reactions are involved.Because these complex phenomena are also bottlenecks for the establishment of all-sol id-state batteries(ASSB),we conducted multi-scale analysis using combined multi-measurement techniques,to directly observe charge/discharge reactions at hierarchical scales for the oxide-type ASSB using Na as the carrier cation.In particular,all of measurement techniques are applied to cross-section ASSB in the same cell,to complementarily evaluate the elemental distributions and structural changes.From Operando scanning electron microscopy-energy-dispersive X-ray spectroscopy,the Na concentration in the electrode layers changes on the micrometer scale under charge/discharge reactions in the first cycle.Furthermore,Operando Raman spectroscopy reveal changes in the bonding states at the atomic scale in the active material,including changes in reversible structural changes.After cycling the ASSB,the elemental distributions are clearly observed along with the particle shapes and can reveal the Na migration mechanism at the nanometer scale,by time-of-flight secondary ion mass spectrometry.Therefore,this study can provide a fundamental and comprehensive understanding of the charge/discharge mechanism by observing reaction processes at multiple scales.
文摘In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were characterized by SEM,NH3-TPD and N2adsorption-desorption isotherms to indicate their intrinsic characteristics.Furthermore,in order to understand the mechanism of deactivation,the resulted green oil was characterized using FTIR and SIM DIS.FTIR results confirmed the presence of more unsaturated constituents and then,more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO,which in turn,could block the pores mouths.Besides the limited hydrogen transfer,N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation,compared with the other catalysts,especially at higher temperatures.
文摘The effects of manganese oxide or ceria promoters on the performance of Na2WO4/SiO2 catalysts for oxidative coupling of methane （OCM） are reported. The OCM reaction was performed in a continuous-flow microreactor at 800℃, atmospheric pressure and under GHSV = 13200 ml·gCat^-1·h^-1.Catalysts were characterized by in situ conductivity measurement, FT-IR spectroscopy, XRD, SEM and temperature programmed reduction analysis. Manganese oxide promoted Na2WO4/SiO2 is considered as one of the active and selective catalysts for OCM reaction. Ceria with high oxygen storage capacity is selected as a proper oxygen activator, providing a higher concentration of the oxy-anion species which is suitable for OCM reaction and compared with manganese oxide. Electrical conductivity of the catalysts was measured in OCM reaction under oxidizing atmosphere, i.e. in the absence of methane. It was found that the trimetallic catalysts, i.e. the catalysts having sodium, tungsten and Mn or Ce species, exhibited similar crystalline structures and morphologies, which lead to suitable bulk properties for the formation of an active and selective catalyst. However, tungsten had significant effect on the texture and redox properties of the catalysts. It was also shown that the crystalline structure of the bimetallic （Na＋Mn or Ce）/SiO2 samples was quite different. This reveals that the metal oxides have significant effect on the extent of crystallization, taking place in the course of interaction of sodium with silica support. Similar conductivities and catalytic performances of （Na2WO4＋Mn or Ce）/SiO2 catalysts propose that the ability of Na2WO4/SiO2 for utilizing oxy-anions formed in presence of different metal oxides is limited.
基金supported by Iran National Science Foundation(No.97015707)。
文摘A series of organic compounds were successfully immobilized on an N-doped graphene quantum dot (N-GQD) to prepare a multifunctional organocatalyst for coupling reaction between CO_(2)and propylene oxide (PO).The simultaneous presence of halide ions in conjunction with acidic-and basic-functional groups on the surface of the nanoparticles makes them highly active for the production of propylene carbonate (PC).The effects of variables such as catalyst loading,reaction temperature,and structure of substituents are discussed.The proposed catalysts were characterized by different techniques,including Fourier transform infrared spectroscopy (FTIR),field emission scanning electron microscopy/energy dispersive X-ray microanalysis (FESEM/EDX),thermogravimetric analysis (TGA),elemental analysis,atomic force microscopy (AFM),and ultraviolet–visible (UV-Vis) spectroscopy.Under optimal reaction conditions,3-bromopropionic acid (BPA) immobilized on N-GQD showed a remarkable activity,affording the highest yield of 98%at 140℃ and 106Pa without any co-catalyst or solvent.These new metal-free catalysts have the advantage of easy separation and reuse several times.Based on the experimental data,a plausible reaction mechanism is suggested,where the hydrogen bonding donors and halogen ion can activate the epoxide,and amine functional groups play a vital role in CO_(2)adsorption.
基金supported by the Grant-in-Aid for Scientific Research(S)(No.JP22H04960)Grant-in-Aid for Scientific Research on Innovative Areas(No.JP19H05788)+1 种基金Grants-in-Aid for Early-Career Scientists(No.JP22K14463)from the Japan Society for the Promotion of Science(JSPS)supported by the Advanced Research Infrastructure for Materials and Nanotechnology Japan(No.JPMXP1223UT0054)by the Ministry of Education,Culture,Sports,Science and Technology(MEXT).
文摘1.Introduction Grain boundaries(GBs)in polycrystalline materials exhibit unique atomic structures due to the lattice disorder,resulting in properties that are distinct from the bulk[1-5].Doping foreign atoms in the GBs has become one of the most popular strategies for modifying material properties,such as grain growth behaviors,microstructures,and mechanical properties in polycrystals[6-12].These dopants typically diffuse along the GBs at elevated temper-atures and ultimately segregate to preferred GB atomic sites to modify the structures of the GBs[13-15].Consequently,GB seg-regation of dopants has gained significant interests,and a funda-mental understanding of the origin of GB segregation phenomena is crucial for the rational design of materials with unprecedented properties.
基金Funding by the Ministry of Education,Culture,Sports,Science,and Technology(MEXT)Japan,through Elements Strategy Initiative for Structural Materials(ESISM)of Kyoto University+4 种基金by the Japan Society for the Promotion of Science(JSPS)KAKENHI Grant-in-Aid for Young Scientist(B)(Grant No.16K18228)by the European Research Council under the EU’s 7th Framework Programme(FP7/2007-2013)/ERC Grant agreement 290998the Grant-in-Aid for Scientific Research on Innovative Areas Nano Informatics(Grant No.25106005)from the Japan Society for the Promotion of Science(JSPS)by the Deutsche Forschungsgemeinschaft(DFG)for the scholarship KO 5080/1-1by the DFG for their funding within the priority programme SPP 1599.
文摘A first-principles-based computational tool for simulating phonons of magnetic random solid solutions including thermal magnetic fluctuations is developed.The method takes fluctuations of force constants due to magnetic excitations as well as due to chemical disorder into account.The developed approach correctly predicts the experimentally observed unusual phonon hardening of a transverse acoustic mode in Fe–Pd an Fe–Pt Invar alloys with increasing temperature.This peculiar behavior,which cannot be explained within a conventional harmonic picture,turns out to be a consequence of thermal magnetic fluctuations.The proposed methodology can be straightforwardly applied to a wide range of materials to reveal new insights into physical behaviors and to design materials through computation,which were not accessible so far.
基金T.O.acknowledges partial support by a Grant-in-Aid for Scientific Research(C)(Grant Number 21K04648)Grant-in-Aid for Scientific Research on Innovative Areas(Grant Number 19H05792)from the Japan Society for the Promotion of Science(JSPS).
文摘Concentrations of intrinsic and extrinsic point defects in crystalline materials with a bandgap are typically calculated in a constant-μapproach from defect formation energies based on density functional theory.In this work,calculations of thermal and charge equilibria among point defects are extended to a constant-N approach.The two approaches for point-defect equilibria are comparatively demonstrated in the application to Mg_(2)Si doped with Li,Na,and Ag,which is a lightweight and environmentally friendly thermoelectric candidate material.Our results reveal the systematic behavior of defect and carrier concentrations.The dopant atoms form interstitial defects at similar concentrations to substitutional defects at the Mg sites,resulting in significantly reduced free-carrier concentrations compared to the expected values.The developed procedures could be utilized to find an optimal avenue for achieving higher carrier concentrations,e.g.,with regard to annealing temperature and the concentration of dopant atoms,in various semiconductors and insulators.
基金supported by Grant-in-Aid for Scientific Research(A)and Grant-in-Aid for Scientific Research on Innovative Areas“Nano Informatics”(Grant No.25106005)from the Japan Society for the Promotion of Science(JSPS)Support program for starting up innovation hub on Materials research by Information Integration”Initiative from Japan Science and Technology Agency+2 种基金Grant-in-Aid for International Research Fellow of JSPS(Grant No.2604376)and JSPS fellowshipsGrant-in-Aid for Young Scientist(B)of JSPS(Grant No.16K18228)Funding by the Ministry of Education,Culture,Sports,Science and Technology(MEXT),Japan,through Elements Strategy Initiative for Structural Materials(ESISM)of Kyoto University,is also gratefully acknowledged.
文摘Martensitic transformation with good structural compatibility between parent and martensitic phases are required for shape memory alloys(SMAs)in terms of functional stability.In this study,first-principles-based materials screening is systematically performed to investigate the intermetallic compounds with the martensitic phases by focusing on energetic and dynamical stabilities as well as structural compatibility with the parent phase.The B2,D0_(3),and L2_(1) crystal structures are considered as the parent phases,and the 2H and 6M structures are considered as the martensitic phases.In total,3384 binary and 3243 ternary alloys with stoichiometric composition ratios are investigated.It is found that 187 alloys survive after the screening.Some of the surviving alloys are constituted by the chemical elements already widely used in SMAs,but other various metallic elements are also found in the surviving alloys.The energetic stability of the surviving alloys is further analyzed by comparison with the data in Materials Project Database(MPD)to examine the alloys whose martensitic structures may cause further phase separation or transition to the other structures.
